A lab assistant is busy labeling bottles of various liquids. When she is halfway

Question

A lab assistant is busy labeling bottles of various liquids. When she is halfway finished, her friend texts her with some exciting news ands she immediately responds. When she is finished texting, she forgot what liquids are in the left over bottles and she does not know how to label them. There are four unlabeled bottles. She knows they contain either acetone (density 0.792 g/cm^3), benzene (0.899 g/cm^3), chloroform (1.489 g/cm^3), or carbon tetrachloride (1.595 g/cm^3). She takes a sample from one of the bottles. The sample measures 15.0 mL. She puts the sample in a glass beaker to weigh it. The initial weight of the beaker is 48.5 grams. After adding the sample, the weight is 70.8 gram. What was the identity of the liquid? Cars contain catalytic converters. They convert harmful gases in the exhaust to more benign substances. Carbon monoxide for example, is converted into carbon dioxide. Those converters are filled with porous beads that are designed to maximize the surface area. A single 3.0 mm porous bead can have a surface area of 1.0 10^6 cm^2. A certain car has two catalytic converters, each containing 5.0-10^3 beads. Calculate the total surface area of the beads in the two catalytic converters in km^2. A student gently drops an object weighing 15.8 g into an open container that is full of ethanol so that a volume of ethanol spills out. The spilled volume is equal to the volume of the object. The student now finds that the container and its contents weigh 10 5 g more than just the container full of ethanol only. The density of ethanol is 0.789 g/cm^3. What is the density of the object?

Explanation / Answer

1)

Mass of 15mL liquid = Final Weight - Initial Weight

=> 70.8 - 48.5

=> 22.3 grams

Density = Mass/Volume

=> 22.3g/15mL

=> 1.4866 gm/cm^3

Hence the solution is chloroform

2)

Total surface area of the beads = 2 * 5 * 10^(3) * 1.0 * 10^(6) cm^2

=> 10^(10) cm^2

1 km = 10^5 cm

=> 1 km^2

3)

Change in mass = 15.8 - 10.5 = 5.3 grams

This is the amout of ethanol being removed out

Density of Ethanol = Mass of ethanol/Volume of ethanol

Volume of ethanol = 5.3/0.789 = 6.717 mL

Volume of object = 6.717 mL

Density of object = 15.8/6.717 = 2.352 g/cm^3

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